Levels of mitochondrial reactive oxygen species increase in rat neuropathic spinal dorsal horn neurons

Reactive oxygen species (ROS) are toxic agents that may be involved in various neurodegenerative diseases. Recent studies indicate that ROS are also involved in persistent pain through a spinal mechanism. Since the major source of ROS in neurons is mitochondria, mitochondrial ROS generation was examined in dorsal horn neurons of neuropathic rats. Neuropathic rats were produced by L5 spinal nerve ligation and mitochondrial ROS was detected by the mitochondrial marker, Mitotracker Red® CM-H2XRos (MT-Red). Neurons were identified immunohistochemically for the neuronal marker NeuN. The number of MT-Red positive cells was increased 60–100% in the neuropathic dorsal horn. Approximately 75–85% of MT-Red positive cells were neurons. These data suggest that increased mitochondrial ROS in dorsal horn neurons may contribute to central sensitization in neuropathic rats.